private void button2_Click(object sender, EventArgs e)
		{
			TreeLayout tl = new TreeLayout();
			tl.Type = TreeLayoutType.Centered;
			tl.LinkStyle = TreeLayoutLinkType.Cascading3;
			tl.LevelDistance = 50;
			tl.NodeDistance = 60;
			tl.Arrange(diagram);

			foreach (DiagramLink link in diagram.Links)
			{
				link.TextColor = Color.Transparent;
				link.Text = "test " + link.ControlPoints[0].X.ToString();
			}

			for (int z = diagram.Items.Count - 1; z >= 0; z--)
			{
				DiagramLink l = diagram.Items[z] as DiagramLink;
				if (l != null)
				{
					l.CustomDraw = CustomDraw.Additional;
					break;
				}
			}
		}

		private void diagram_DrawLink(object sender, DrawLinkEventArgs e)
		{
			System.Drawing.Brush textBrush = new System.Drawing.SolidBrush(Color.Black);
			System.Drawing.Brush backBrush = diagram.BackBrush.CreateGdiBrush(diagram.Bounds);

			foreach (DiagramLink l in diagram.Links)
			{
				int s = l.SegmentCount / 2;
				PointF p1 = l.ControlPoints[s];
				PointF p2 = l.ControlPoints[s + 1];
				PointF c = new PointF((p1.X + p2.X) / 2, (p1.Y + p2.Y) / 2);

				SizeF textSize = diagram.MeasureString(l.Text, l.Font, int.MaxValue, StringFormat.GenericDefault);
				float w = textSize.Width;
				float h = textSize.Height;
				RectangleF textRect = new RectangleF(c.X - w/2, c.Y - h/2, w, h);

				e.Graphics.FillRectangle(backBrush, textRect);
				e.Graphics.DrawString(l.Text, l.Font, textBrush, textRect, StringFormat.GenericDefault);
			}

			backBrush.Dispose();
			textBrush.Dispose();
		}